Electric heating element.



` invention; Figs. 2 and 3 i parts may be results.

DAVI) HUNTLEY, DE LONDON,

ENGLAND.

ELECTRIC HEATING ELEMENT.

Specification of Letters Patent.

Patented Dec. 9, 1913.

Application led February 8, 1913. Serial No.. 747,174.

To all tti/1,0m t may concern:

Be it known that l, DAVID HUNTLEY, a subject of the Kingjot England, andresi# dent; of `London, England, have invented certain new and userulimprovements in New or improved Electric Heating Elements, of which thefollowing is a specification. l

The object of this invention is to produce a strong, compact electricheating element, of simple construction, easily handled, readilyreplaceable, and in which the various removed with great facility and bypersons of ordinary skill but with out technical or electricalknowledge.

Heretofore mica and asbestos have been employed as insulators incombination with resistance wires, strips or tapes in the constructionot electric heating elements, but it has been found that when heated toa high'temperature the mica or asbestos chemically atl'ects the metal oralloy and produces more or less rapid oxidation, and a reduction of thesectional area-of the Wire, strip, or'tape, and consequently sets up agreater resistance locally and ultimately causes the destruction of themetal. This is believed to be due to the presence of metallic or othersubstances in the mica or asbestos which produce chemical action when incontact with the metal or alloy, which action is increased Y by thepresence ot the electric current but it has been' found that neither ofthese insulating materials used alone yield satisfactory Othersubstances such as porcelain, glass, fireclay, quartz, or the like, havebeen employed for inclosing or supporting the resistance wires, strips,or tapes, but I pret'er to use a combination of insulators and supportsas hereinafter described,

Figure 1 of the acconn'ianying drawings illustraties in front view anelectric heating elementconstructcd in accordance with my arelongittuilinal edge and end Views respectively of Fig. l; Fig, 4 isafront elevation ot' a heating' stove illustrating one application ot myimproved i electric heating elements; and Fig.` 5 is a side elevation ofthe same stove with the portion upon which the heating elements aremounted turned down to," ythe purpose ot' examination or repairs.

Similar letters or reference relate to like parte` in all tbe figures ofthe drawings.'

Referring to Figs. l, 2 and t-. n is the base tormedof tireclay'forexample, or ot other 'plate or slab are connected may be left at the topmaterial of a. refractory and highly electri cal insulating character,in the face of which is molded or otherwise formed a recess b preferablyof zigzag shape with rounded corners as sho n, and'extending from end toend of the base a. c is a helical Wire coil' ot' metal or alloy ofrelatively high resistance which is laid loosely into the recess I). dis a plain plate or slab of quartz or fused silica, preferably of thesame length and width as the i'reclay base a and arranged t0 cover theresistance coil c. In some cases the outer surface of the plate or slabal may be corrugated to form a greater surface for radiation or brokenup into any convenient pattern. The iireclay base .o and the quartztogether at one or both ends by means of caps or clamps e which may beconveniently formed of sheet brass or other metal bent or stamped intothe shape shown and carrying terminal or contact screws f by which theends of the resist-ance coils c are removably connected to the caps orclamps e for conducting the current vinto the said resistance coils c.Or such connection may be effected in any other suitable manner.

If desired more than one resistance coil c may be laid into the recessb, or instead of such coils one or more strips of metal or alloy ot'relatively high resistance may be employed.

I'soinetimes inclose the back ireclay base a 1n a metal or other closedcasing or jacket y (Fig. 3) with a Space l2,`

between, thereby preventing too rapid radiation of the heat from theback of the tireclay portion t of the element. And when it is desiredto'carry oil' the heat, openings ing or jacket g, thereby allowingforthecirculation of the air.

The metal caps or clamps c arepreferably provided with a flange c' bywhich any desired number of elements may be readily connected to a metalconductor plate by means oi screwed studs 7' and wing-nuts (Figs. 4l and5) or by other suitable devices. And 'in order to retain the quartzplate or slab (Z firmly in place, one or more portions of the caps orclamps e may be slit, as shown at m t'or example, and bent' inward so asto bear upon the quartz plate or slab with a more or less yielding orresilient, pressure.

These completed elements may be employed for a great variety ot'purposes, such portion of the and bottom of the casssl Cri

electric radiators, electric ovens7 or other electric cooking 0i'heating appliances, their shape and simple Construction enabling them tebe applied in a very easy and ef- Yl'eel'ive. manner. For exemple, theynnLy be made to forni horizontal luminous bays in in electric radiatorstove, :1nd Lhey muy be provided wiix bent el' corrugated ie'lecingsurfaces al mie bzicli thei'ee'f, se ab' 'ie :is-eist or increase thecirculation 01 the mii, und ielleet ille heat :myn: Buch :in electricrsidiaoi' suive is illnrfei'ulfed in Figs. l und in which fourelein'eiiis constructed as hereinhelei'e described Willi reference Lo.Fil l 2 land 3 are shown inuunied in u heiizen tul peeitien (ly meansof 'ille wingnus 17a) upon vei'ieally disposed conductor plates n whichare attached by Screws 0 and nnte ',v le die buse plaine y lil-0in whichthey iii'e el tiieully insulated by means eil Lhe mishe, v", rlhe brisepluie g is mounted ngen the Duel; plante :i el" the Stove :it zi Suimbiedi tenue therefrom :is shown, and @bhe seid heel: :plaie s ishinge-jointed at t ie the ixed pei'tzien u ef the steve so hat may heznned down inte the position. shown in if@ 5.2 for examination ori'epuii'ea oy be Lui-ned up intelhe Closed oi' working `pesition andiet-:lined therein by the turn-but- 'lun er. w :ire beni plaies el'bleek plzwirgheo. steel ei the like :itin/hed te the Las@ niet@ Qbetween lle eleinenls S0 is te give lille z l l l l l l l l l l i l l il i in relation to the switches 0J thai. the whole or part of theelements muy be :in'inehed on ei' eli' aeeoiding le reqnii'einent'-,

ln Figs. l and the heated dir ehznnbei fix ie seiniiaed frein the lmclsof the elements ny die bei-e plaie g, bul; it

that portions the eid plaie may he se fut and lient as lie hiciese he@if each elen'ivntfse ihm; ih@ l li su *es el lhe lii'eeiziy lmes y,'wen l tm'in p rtien# the well el'. me l n' chain-- bei' ./LX.

The easing i5 em'e ed :it the freni., by i am'een e; gm@ v wing new:l'dlljf7 de `C1filzed my i veniion, *what l elziiin and desil'a'; Lesecure l an elem' lll ie combihinged menieine',

ies el condi ed apen the p w zii-illy pr-93 e Li n liars and fre-1n heplaie and he for eeein'nig sind conduction u1 n plate and ineens fereeni'elling ehe el Cirie Supply.

in eslnnony wheres' in y hund in pres ebvimxs

